Fix browser text selection during icon drag

- Add e.preventDefault() in handlePointerDown to prevent text selection
- Add @dragstart.prevent to prevent native browser drag
- Add select-none and @selectstart.prevent to workspace
- Add mouseleave event listener to reset drag state when leaving window
- Refactor grid positioning to use consistent iconPadding constant

package.json

@@ -1,7 +1,7 @@
 {
   "name": "haex-hub",
   "private": true,
-  "version": "0.1.9",
+  "version": "0.1.10",
   "type": "module",
   "scripts": {
     "build": "nuxt build",